Shark researchers in Australia, where shark attacks have increased lately, have developed a new wetsuit design making use of research that shows that sharks may avoid certain colors and patterns that fish use to warn sharks that they are toxic.
Other designs are focused on stealth concepts by hiding the outline and shape of wetsuits and surf boards. These designs are based on camouflage stripes and patterns, which make the diver, surfer or swimmer much less visible in the water.
When you think about it, donning a black wetsuit that makes the swimmer resemble a seal, one of shark's favorite foods, is just asking for trouble.
Similarly swimming gear and wetsuits are often brightly colored and really stand out against the color and pattern of the ocean. This is particularly relevant for safety jackets and life vests. Research has shown that many survivors of boat sinkings get taken by sharks while waiting to be rescued.
For many years, various attempts have been made to prevent shark attacks on surfers, swimmers and scuba divers. This includes:
► Electronic devices that release sounds and vibrations that sharks do not like.
► Various chemicals have been developed as shark repellents, that either are disliked by sharks or cloak the swimmer's smell and odor. Sharks have renowned sense of smell, especially for blood and body fluids.
► Some devices resemble mini plastic swimming pools. The idea is that people who fall into the water from capsized boats or plane crashes, can climb into these floating chambers which would stop the release of body fluids into the water to prevent their odors attracting sharks. These floating chambers also disguise the shape of the person in the water.
For the recent study researchers looked at using stealth techniques to hide the swimmers of mimicked the danger signals that fish use to avoid being attacked. Experiments were conducted with various stripe patterns, contrasts and colors to see whether they provided a 'leave me alone, or else' warning signal to sharks to keep away.The patterns are used by fish to warn predators that they are toxic.
The other patterns trialled were designed to hide the outline and shape of the swimmer, so that he or she is less visible in the water. In a sense this is designed to provide a swimmer with an invisible cloak which confuses the shark and makes the swimmer less visible.
The idea is that sharks may be able to track odors in the water to the general vicinity but their sight, which they use for the final attack will be confused by the wet suit patterns. Most wetsuits you can buy now are black or very brightly colored with contrasting patterns. Such colors and patterns are highly visible to sharks
Stickers have also been developed that either highlight the board with warning stripes or make the board less visible from below.
What this means is that they may depend on contrast (block and white) to distinguish objects against the gray (blue) background of the ocean. This means that many brightly colored wet suits may really stand out and could attract sharks.
How does one know that sharks are color blind, you may ask?
The researchers used a procedure called micro-spectrophotometry to examine how many types of cone photoreceptors occur in the eyes of sharks. Humans and many other vertebrates have three cone types that are sensitive to red, blue and green light. However, most sharks so far tested were found to only have one photoreceptor type.
This means that most sharks can only see one color, which is equivalent to saying they can only see shades of gray in a contrast range from black to white.
The finding that sharks are color blind has many important implications:
► Most marine safety clothing such as life jackets have traditionally been designed with bright colors and contrasts to stand out in the ocean. These designs may need to be reviewed because they may make people in the ocean more attractive to sharks. Designs are needed that sharks cannot see but humans can.
► Most swimming costumes such as board shorts and rash jackets, are also designed with bright colors and contrasting patterns which may be highly visible and attractive to sharks. This may not be due of the bright colors but because of the high contrast between the panels.
► The study may also prompt a re-design of lures used for long-line fishing to make them less attractive to sharks.